Cooling device for strands that are to be cast continuously

ABSTRACT

The invention relates to a cooling device for strands that are to be cast continuously, in particular for steel slabs of different widths. Spray nozzles connected to pipe conduits for supplying a coolant are distributed over the width and the length of the strand. The hitherto known cooling devices used in continuous casting have the disadvantage that the cooling effect becomes irregular when the slab size is changed. This disadvantage is eliminated by the device of the invention by arranging the spray nozzles horizontally displaceable transverse in relation to the strand surface.

1 Aug. 5, 1975 United States Patent [191 Bachner Uni/283 i 1 COOLINGDEVICE FOR STRANDS THAT IHUUESS M1974 Bushkm ct Lll.

ARE TO BE CAST CONTINUOUSLY [75] Inventor: Ernst Bachner. Linz, AustriPrimary L.\tllllill&'l'RUhCft S. Ward Jr.

.ixrismm h',\ulnim'rMichael Mur Assigncc:

\"ereinigte Osterreichische Eisen- .'iII(II'H( Again. or Finn-Brumbuugh,Graves, Donohuc & Raymond [22] Filed1 1211 Appl. No: 489.358

The invention relates to u cooling dcvicc for strands that are to becast continuously. in particular for steel slabs of different widths.Spray nozzles connected to Foreign Application Priority Data 1 1 r v(wk/7' pipe conduits for supplying u cool-tint are distributed over thewidth und the length of the strand. The hithcrtu known cooling devicesused in continuous casting 2 H 1 al Md .1 7- 7.. 88 l 93 3 C L n havethe disadvuntagc that the cooling effect becomes irregular when thc slahsize is changed. This disadvanh C r. a e

we 4 5 U! 3 2 tuge is eliminated b the device of the invention by ur-3.499.456 Rcrccich ct :il. Hui/Z33 S X 5 Claims. 2 Drawing FiguresCOOLING DEVICE FOR STRANDS THAT ARE TO BE CAST CONTINUOUSLY Theinvention relates to a cooling device for strands that are to be castcontinuously, in particular for steel slabs of different widths, withspray nozzles distributed over the width and length of the strand. whichnozzles are connected to pipe conduits for the supply with the coolingmedium.

Known cooling devices for continuous casting plants. as they aredescribed in the Austrian Pat. Specifications Nos. 233,l86 and 265.550comprise a stationary system of spray nozzles for water or mixtures ofwater and a gaseous medium. e.g. compressed air, which nozzles aredirected towards the strand surface and are con nected to pipe conduits.The spray nozzles are arranged between the support rollers, respectivelythe guiding rollers for the strand. In order to achieve a uniformcooling of the strand, spray nozzles with a flat characteristic and astaggered arrangement of the nozzles, seen in transport direction of thestrand, have been proposed; moreover it has been known to supply thespray nozzles groupwisely with a cooling agent, wherein the capacity ofthe cooling agent of the one group selectively alternates, cyclicallywith the altered capacity of the cooling agent of another group. Finallyit has also been recommended to provide individual rows of spray nozzlesto be completely separately capable of being regulated or turned off,respectively, in particular the nozzles lying in the range of the edgesof the strand, so that the strand edges be not cooled too strongly,which leads to the formation of cracks. The turning off of individualspray nozzles has the disadvantage that, when the nozzles remain turnedoff for a longer period. im purities of the cooling agent are depositedin the pipe conduits, which may lead to a choking of the nozzle bores,when the nozzles are turned on again.

All known cooling devices used in continuous casting have thedisadvantage that the cooling effect becomes varied and irregular, whenthe slab sizes are changed; because with certain sizes it is inevitablethat the strand edges come to lie in the range of the fixedly mountedspray nozzles and are cooled too strongly with width fluctuationsoccurring in practice that lie between approx. 800 mm and up to approx.2,500 mm the strand edges may get into the middle range of the coolingdevice, where a selective cooling is not possible. This means that, whenthe width of the strand is changed, complicated technical installations,which are liable to disturbances, become necessary, because with a largenumber of spray nozzles one has to operate with extremely small nozzlebores, which tend to become choked easily.

It is the object of the invention to avoid these difficulties and toprovide an operationally reliable, simple cooling device for strands ofdifferent widths, wherein the number of spray nozzles can be reduced andthe diameter of their bores can be enlarged.

In a cooling device of the above described type this problem is solvedby arranging the spray nozzles transverse in relation to the strandsurface capable of being displaced horizontally.

A preferred embodiment consists in that the spray nozzles can be movedoscillating within two limit lines, which can be adjusted in a freelyselectable distance from the strand edges.

Suitably at least two spray nozzles per strand side are arrangeddisplaceably side by side in a plane perpendicular to the strandsurface, wherein their displacement range is smaller than half thestrand width.

Furthermore the spray nozzles can be moved towards each other or awayfrom each other mirror-symmetrically in relation to the strand center.

A development of the invention consists in that the spray nozzles seenin transport direction of the strand are arranged staggered in a mannerknown per se and are combined in groups, wherein the degree of staggeredarrangement advantageously corresponds to the displacement range.

The invention will now be described in more detail by way of examplewith reference to the accompanying drawings.

FIG. I shows a side view ofa continuous casting plant for slabs,illustrated schematically.

FIG. 2 is a view of the width of the slab below the mold, wherein forreasons of better clarity the supportand guiding rollers are not shown.

In FIG. I, 1 denotes a water-cooled. vertically oscillating mold, fromwhich a strand 2 is withdrawn. The rollers for supporting, guiding andbending the strand 2 from the vertical to the horizontal are denotedwith 3 and the driven withdrawing rollers are denoted with 4; thewithdrawal direction is indicated by the arrow 5. The cooling devicearranged to follow the mold I, the so-called secondary cooling zone,comprises three sec tions 6, 7 and 8, formed by the cooling-water pipes9, l 1, l2 and the spray nozzles 10. The spray nozzles 10 are arrangedbetween the rollers 3 in all three cooling sections. According to theinvention the spray nozzles are, groupwise together with the pertainingcoolingwater-supply pipes 9, II, 12, horizontally displaceable,transversely to the strand surface, as can be seen in detail from FIG.2.

Each section 6, 7, 8 of the cooling system is provided with two spraynozzle rows per strand side, which spray nozzles are parallel inrelation to the strand center 20 and are fixedly connected with thepipes 9, I], 12. Perpendicularly to the pipes 9, I I, 12, further pipesI3, l4, 15 are connected, which are horizontally displaceable in slidingbearings I6, so that the pipes 9, II, 12 oscillate between the limitlines 17, [8 about the range a. As drive means for the pipes variousinstallations known to the man skilled in the art may be used, as e.g.hydraulically or pneumatically operable, doubly actuated pistons,spindles with an electromotoric drive motor, capable of altering thedirection of rotation, crank rods, etc, wherein the movement backwardand forward in the direction of the double arrows in uniform, e.g,sinusoidal or irregular in such a way that eg. the rest period of thespray nozzles 10 in the range of the strand center 20 or in the range ofthe limit lines 17 adjacent thereto, respectively, is bigger than in therange of the strand edges 19 or in the range of the limit lines 18,adjacent thereto, respectively. In FIG. 2 the pipes 9, I2 are arrangedstaggered in relation to the pipes 11, so that by displacement into thepositions 9'. II. I2, a plurality of screwshaped lines results, whichrepresent the geometrical locus of the points of impact of the waterjets on the moved strand surface. By balancing thestrandwithdrawal-speed and the oscillation of the spray nozzles 10 inconnection with the amount of cooling water and the angle of opening ofthe spray nozzles (the spray characteristic) a uniform cooling of thestrand 2 can easily be achieved. When the strand width is changed onlythe position of the limit lines I8 and the oscillation stroke a have tobe newly stipulated, which can, in the case of an electromotoric drive,be carried out by adjusting the limit switch. The distance b of thelimit lines 18 from the strand edges 19 is fixed corresponding to theopening angle of the spray nozzles, so that a subcooling of the strandis avoided. The distance between the limit lines 17 also depends on thespray characteristic of the nozzles used, i.e. it is to be chosen insuch a way that also the middle zone is completely actuated by thecoolant, when the spray nozzles are in one final position 9, ll, 12.

Of course different embodiments and variations of the invention arepossible. The number of spray nozzles forming a group 6, 7, 8 mayfluctuate between i and n, preferably between 2 and n; with narrow slabsone can do with one single spray nozzle oscillating forward and backwardbetween the lines 18 in a plane between the rollers 3 and with wideslabs two spray nozzles 10 in a plane are sufficient, which are thenarranged, as illustrated in FIG. 2, and are moved in opposite directionrelative to each other. Also the number of spray nozzles 10 of a grouparranged one following the other in the direction of the movement 5 ofthe strand 2 may vary between 1 and n. Each group can therefore comprisea different number of nozzles; it is however important that the spraynozzles be arranged mirror-symmetrically in relation to the strandcenter and that the horizontal movement of the pipes l3, l4, l5correspond in one and the same plane on both halves of the strand. lf asshown in this embodiment only two nozzles 10 each are used between therollers 3, the nozzles can have a correspondingly big exit cross sectionwhich can hardly be choked by impurities contained in the coolant; theoperational reliability of the device is thus decreased and much lessmaintenance of the secondary cooling zone is necessary, because in thecoolant system there is no need for complicated control and regulatingdevices.

What I claim is:

l. in a cooling device for strands that are to be cast continuously, inparticular for flat steel slabs of different widths, said strands havingedges and a pair of parallel flat surfaces, said cooling devicecomprising a plurality of spray nozzles distributed over the width andalong a given length of the strand, the spray nozzles being connected topipe conduits for supplying them with a coolant, the improvement inwhich the spray nozzles are movable along horizontal straight line pathswithin a displacement range less than the width of said strand, saidpaths being transverse to the strand surface.

2. ln a cooling device for strands that are to be cast continuously, inparticular for steel slabs of different widths, said strands havingedges and a surface. said cooling device including a plurality of spraynozzles distributed over the width and along a given length of thestrand, the spray nozzles being connected to pipe conduits for supplyingthem with a coolant, the improvement in which, said spray nozzles aremovable horizontally and transverse to the strand surface in anoscillatory manner between two limit lines, the limit lines beingadjustable within a freely selectable distance from the edges of thestrand.

3. In a cooling device for strands that are to be cast continuously, inparticular for steel slabs of different widths, said strands havingedges and a surface, said cooling device including a plurality of spraynozzles distributed over the width and along a given length of thestrand, the spray nozzles being connected to pipe conduits for supplyingthem with a coolant, the improvement in which, there are at least twospray nozzles on each side of the strand arranged side by side and in aplane perpendicular to the surface of the strand, and said nozzles aremovable horizontally and transverse to the strand within a displacementrange smaller than half the width of the strand.

4. In a cooling device for strands that are to be cast continuously, inparticular for steel slabs of different widths, said strands havingedges and a surface, said cooling device including a plurality of spraynozzles distributed over the width and along a given length of thestrand, the spray nozzles being connected to pipe conduits for supplyingthem with a coolant, the improvement in which, said spray nozzles aremovable towards and away from each other, horizontally and transverse tothe strand, in mirror-symmetry with respect to the center of the strand.

5. In a cooling device for strands that are to be cast continuously, inparticular for steel slabs of different widths, said strands havingedges and a surface, said cooling device including a plurality of spraynozzles distributed over the width and along a given length of thestrand, the spray nozzles being connected to pipe conduits for supplyingthem with a coolant, the improvement in which, said spray nozzles aremovable horizontally and transverse to the strand within a certaindisplacement range and are arranged in groups along the direction ofmovement of the strand, the nozzles of one group being staggered inposition relative to the center of the strand with respect to thenozzles of adjacent groups by a distance substantially equal to saiddisplacement range.

l i 1k UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OFCORRECTION PATENT NO. 3,897,906

DATED Aug. 5, 1975 INVENTOR(S) Ernst Bachner It is certified that errorappears in the above-identified patent and that satd Letters Patent arehereby corrected as shown below:

Col. 1, line 42, "strongly with" should read strongly.

With--; and

Col. 3, line 35, "decreased" should read increased-.

Signed and Scaled this seventh Day of 0cto'b-erI975 [SEAL] Arrest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN ('nmmissirmer ofParents and Trademarks

1. In a cooling device for strands that are to be cast continuously, inparticular for flat steel slabs of different widths, said strands havingedges and a pair of parallel flat surfaces, said cooling devicecomprising a plurality of spray nozzles distributed over the width andalong a given length of the strand, the spray nozzles being connected topipe conduits for supplying them with a coolant, the improvement inwhich the spray nozzles are movable along horizontal straight line pathswithin a displacement range less than the width of said strand, saidpaths being transverse to the strand surface.
 2. In a cooling device forstrands that are to be cast continuously, in particular for steel slabsof different widths, said strands having edges and a surface, saidcooling device including a plurality of spray nozzles distributed overthe width and along a given length of the strand, the spray nozzlesbeing connected to pipe conduits for supplying them with a coolant, theimprovement in which, said spray nozzles are movable horizontally andtransverse to the strand surface in an oscillatory manner between twolimit lines, the limit lines being adjustable within a freely selectabledistance from the edges of the strand.
 3. In a cooling device forstrands that are to be cast continuously, in particular for steel slabsof different widths, said strands having edges and a surface, saidcooling device including a plurality of spray nozzles distributed overthe width and along a given length of the strand, the spray nozzlesbeing connected to pipe conduits for supplying them with a coolant, theimprovement in which, there are at least two spray nozzles on each sideof the strand arranged side by side and in a plane perpendicular to thEsurface of the strand, and said nozzles are movable horizontally andtransverse to the strand within a displacement range smaller than halfthe width of the strand.
 4. In a cooling device for strands that are tobe cast continuously, in particular for steel slabs of different widths,said strands having edges and a surface, said cooling device including aplurality of spray nozzles distributed over the width and along a givenlength of the strand, the spray nozzles being connected to pipe conduitsfor supplying them with a coolant, the improvement in which, said spraynozzles are movable towards and away from each other, horizontally andtransverse to the strand, in mirror-symmetry with respect to the centerof the strand.
 5. In a cooling device for strands that are to be castcontinuously, in particular for steel slabs of different widths, saidstrands having edges and a surface, said cooling device including aplurality of spray nozzles distributed over the width and along a givenlength of the strand, the spray nozzles being connected to pipe conduitsfor supplying them with a coolant, the improvement in which, said spraynozzles are movable horizontally and transverse to the strand within acertain displacement range and are arranged in groups along thedirection of movement of the strand, the nozzles of one group beingstaggered in position relative to the center of the strand with respectto the nozzles of adjacent groups by a distance substantially equal tosaid displacement range.